How do I know how many time points and how many slices does a subject image set include? Let's take the case of resting state images of a specific subject encounter.
So far, I used to download the zip which included 6,720 dicom files and then I knew the number of slices because SPM tells me that number when running the preprocessing (say, 48), and I knew the number of time points because after the preprocessing I got 140 nifti files.
How can I know these numbers (140 and 48) beforehand?
You can't know a priori how many slices and volumes will be in ADNI fMRI data. I would recommend using dcm2niix to convert the data from DICOM to NiFTI-1 format which should generate a BIDS file containing the information you are looking for OR you can load the .nii file and interrogate the header to size information. If you prefer to use a different conversion tool, then you can read the dicom header information and sort out volume sizes and numbers of volumes programmatically. There are multiple vendors, multiple software revisions, and multiple protocols -- all of these can affect details of the sizes. Nominally there will be a 48 slice acquisition with TR approximately 3 seconds and a 64 slice acquisition with TR approximately 600-750ms. All the images are supposed to run for approximately 10 minutes of wall clock time.
